JPH0210862Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is a spool valve formation in which the spool has hysteresis when slidingly displacing between a first position and a second position. The present invention also relates to improvements in hydraulic control valves for automatic transmissions.

(Prior art) Some hydraulic control valves for automatic transmissions include spool valves and shift valves that control the supply of hydraulic pressure to hydraulic actuators such as brakes and clutches that switch the power transmission path of automatic transmissions. For example, when the spool to be slid and displaced is in the first position, downshifting is controlled, while when it is in the second position, upshifting is controlled. In order to change the speed change characteristics for downshifting and upshifting depending on the operating condition of the engine, the first position and the second position are
It is necessary to provide hysteresis between the positions. In other words, if the shift characteristics are determined by the vehicle speed and the accelerator opening, the vehicle speed during upshifting can be greater than the vehicle speed when downshifting if the accelerator opening is the same. It is necessary to provide this difference in vehicle speed with respect to the accelerator opening as hysteresis (it can also be seen as a difference in the accelerator opening with respect to the vehicle speed).

To explain this kind of hysteresis in detail, in the case of the above-mentioned shift valve, there is a governor that introduces governor pressure in accordance with the vehicle speed into the spool guide hole of the main body into which the spool is slidably inserted. The spool has a governor pressure land portion (large diameter portion) that constantly receives this governor pressure. In addition, there is a first throttle pressure land that always receives pressure from one of the two throttle pressure introduction ports, and a second throttle pressure land that receives pressure when the other throttle pressure introduction port is opened. A land portion is formed. The first position and the second position are switched by the balance between the pressing force in one direction due to the governor pressure of the spool and the pressing force in the other direction due to the throttle pressure. Since the two throttle inlets are both open, the throttle pressure acts on both end faces of the two throttle pressure lands (step end faces), and conversely, in the second position, one throttle pressure inlet is closed. As a result, the throttle pressure acts only on the end face of the first throttle pressure land portion, and by varying the pressure receiving area on which such throttle pressure acts, the above-mentioned hysteresis is provided. ing.

By the way, in an automatic transmission, when the accelerator opening is depressed so much that it exceeds the set opening, the so-called kick-down region occurs, and the shift characteristics, that is, the acceleration, are different from the normal shift region below the set opening. The transmission characteristics are designed to emphasize the following. Even in such a kickdown region, it is necessary to provide hysteresis by making the shift characteristics different between upshifting and downshifting as described above. Conventionally, in order to bring about this hysteresis, as mentioned above, a throttle pressure introduction port for kickdown, through which throttle pressure is introduced during kickdown, is opened in the spool guide hole, and at the same time,
This was accomplished by providing two corresponding land portions (see Japanese Patent Laid-Open No. 55-36612).

However, as mentioned above, in the conventional system, in order to provide one type of hysteresis between the first and second positions of the spool, at least two dedicated oil ports for control (as described in the above publication) are required. In this case, we needed a down pressure inlet and an outlet) and two corresponding lands.
Not only does the structure become extremely complex, but the hydraulic control valve also becomes larger (in particular, the axial length of the spool becomes longer), and the spool's sliding and inertia increase accordingly. Problems arise, such as poor performance (responsiveness of the spool).

(Purpose of the invention) The present invention solves the above-mentioned problems, and although it can provide hysteresis between the first and second positions of the spool, the overall structure is simple and compact. The purpose of the present invention is to provide a hydraulic control valve for an automatic transmission that enables the following.

(Structure of the invention) The present invention takes into consideration that the above-mentioned problem arises because the conventional one uses only the end surface of the land portion, in other words, the outer circumferential portion of the spool as a pressure receiving part of the control pressure. A pressure receiving section for this control pressure is configured inside.

Specifically, the spool has a hollow portion formed therein, and a communication port that is connected to the hollow portion and opens to the outer circumferential surface of the spool. When the spool is in the first position, the communication port communicates with the control pressure introduction port, and conversely, when the spool is in the second position, the communication port is blocked from the control pressure introduction port. When in the first position, the control pressure is applied to the inner end surface of the hollow part, while in the second position, the control pressure is not applied to the inner end face of the hollow part.

(Example) An example of the present invention will be described below based on the attached drawings. In this example, a case where the present invention is applied to a 2nd and 3rd shift valve for switching between 2nd and 3rd speeds will be described. be.

First, regarding the shifting characteristics between 2nd and 3rd speeds,
To explain with reference to FIG. 5, the characteristic line X shown by the solid line in the figure shows the shift from 2nd speed to 3rd speed (upshift), and the characteristic line Y shown by the broken line in the figure shows the case of the shift from 3rd speed to 2nd speed (upshift). (downshift). Both characteristic lines X and Y have hysteresis so that the vehicle speed when shifted for the same accelerator opening is different, and this hysteresis is caused by the fact that the accelerator opening becomes the set opening. The normal shift range below 7/8 is different from the kickdown range above 7/8, and in the kickdown range the vehicle is shifted at a higher speed than in the normal shift range in order to meet acceleration demands.

Next, a 2, 3 shift valve to which the present invention is applied will be explained with reference to FIGS. 1 and 2. In the figure, 1 is a main body, and the main body 1 is formed with a spool guide hole 2 that extends long in the left-right direction, and nine ports 3 to 3 that open to the spool guide hole, respectively.
11 is formed. These multiple ports 3 to 1
Among ports 1, governor pressure PG corresponding to the vehicle speed is always introduced as a control pressure to port 3, and throttle pressure PTH corresponding to the accelerator opening is constantly introduced to ports 5 and 9 as other control pressures. The throttle pressure PTH as a control pressure is introduced into the port 10 only in the aforementioned kickdown region, and the ports 4, 6, 11
is used for drains. Further, port 7 is connected to a hydraulic actuator (not shown) for switching the power transmission connection path of the automatic transmission,
Port 8 is configured to introduce line pressure PL as working oil pressure for this hydraulic actuator.

A spool 12 is fitted into the spool guide hole 2 so as to be slidable in the left and right directions in the figure, and this spool 12 has five land portions 13 from first to fifth.
~17. Spool 12 like this
is capable of assuming a first position located at the left throttle end shown in FIG. 1 and a second position located at the right throttle end shown in FIG.
Among these five land portions 13 to 17, the first land portion 13 is for receiving the governor pressure PG at all times, and the second land portion 14 is for opening and closing the port 5, and in the second position where it is opened, the throttle is Pressure PTH
It is assumed that the pressure will be received. Further, the third land portion 15 is used for communicating with and blocking ports 6 and 7.
The ports 6 and 7 are blocked in the first position, and the ports 6 and 7 are blocked in the first position.
The position is designed to allow communication. moreover,
The fourth land portion 16 constantly receives the throttle pressure PTH from the port 9 and opens and closes the port 8. The fourth land portion 16 communicates with the port 7 in the first position, and communicates with the port 7 in the second position. It has become something that blocks out. In the first position where port 7 is communicated with port 8, the second speed state is set (downshift), and in the second position where port 7 is communicated with port 6, the third speed state is set (upshift). It's getting old.

The fifth land portion 17 of the spool 12 has a third
As shown in FIG.
8 is formed, and this hollow part 18 is connected to the spool 12.
The inside of the hollow portion 18 is opened at the left end face of the hollow portion 18, and the inside of the hollow portion 18 is cut off from the port 11 in the first position, and communicated with the port 12 in the second position. Furthermore, a communication port 19 extending in the radial direction is formed in the fifth land portion 17 at a substantially intermediate portion thereof in the axial direction. The communication port 19 has one end opened in the hollow portion 18 and the other end opened in the outer peripheral surface of the fifth land portion 17, and communicates with the port 10 when the spool 12 is in the first position. while in the second position, port 1
It is designed to be cut off with 0.

Here, _the inner diameter of the spool guide hole 12 is set as D ₁ to D ₆ as shown in FIG.
They are D ₂ , D ₃ , D ₅ , D ₄ , and D ₆ . Further, the outer diameter of each land portion 13 to 17 is such that the first land portion 13 is
_D1 , the second land portion 14 is _D2 , the third and fourth land portions 15 and 16 are _D3 , and the fifth land portion 17 is D2.
It is said to be _D4 . The outer diameter of the cylindrical portion 20 extending leftward from the fifth land portion 17 is _D6 . Note that D ₅ is provided as a communication portion so that the pressure from the port 10 acts on the left end surface 17a of the fifth land portion 17 at both the first position and the second position. 10a, or in other words, to increase the opening width of the port 10 relative to the spool guide hole 2.

Next, regarding the balance of forces for slidingly displacing the spool 12, we will discuss downshifting from 3rd gear to 2nd gear in the normal shift range, upshifting from 2nd gear to 3rd gear, and 3rd gear in the kickdown range. →Downshift to 2nd gear and 2nd gear →
The explanation will be divided into four cases including an upshift to the third speed, but prior to this explanation, the individual forces that push the spool 12 to the left or right in the figure will be explained.

First, the spool 12 is always urged by a spring 21 toward the right, that is, toward the second position, with a force F. In addition, the governor pressure PG is
It presses the spool 12 leftward, that is, toward the first position, and acts on the entire stage area A ₁ corresponding to the outer diameter D 1 _of the first land portion 13 . Throttle pressure
PTH (including during kick-down) is for pushing the spool 12 to the right.To explain this in order, the throttle pressure PTH from port 5 is applied only at the second position.
It acts on the pressure receiving area A ₂ obtained by subtracting the total cross-sectional area of the third land portion 15 from the total cross-sectional area of the land portion 14 . Throttle pressure from port 9
PTH is calculated from the total cross-sectional area of the fourth land portion 16 to the fifth land portion 16.
Pressure-receiving area after subtracting the total cross-sectional area of the land portion 17
It acts on A ₃ .

Here, the throttle pressure PTH from port 10 is
Although it is introduced only in the kick-down area, in the first position, the fifth land portion 17
It acts on the total cross-sectional area A ₄ of . In other words, the throttle pressure PTH from port 10 is
As a result of being introduced into the hollow portion 18 through the communication port 19, it also acts on the inner end surface 18a of the hollow portion 18 and the left end surface 20a of the cylindrical portion 20, while the left end surface of the fifth land portion 17 17a as well, as described above. Even in the second position, the communication port 1
9 is cut off from the port 10, and the fifth land portion 17
Since the port 10 faces only the end surface 17a, it ultimately acts on the area _A5 of the end surface 17a. Note that the line pressures PL cancel each other out as pressing forces in the left and right direction, and do not contribute to the pressing force on the spool 12 in any way.

As described above, the force that presses the spool 12 toward the right, that is, toward the second position, against the governor pressure PG can be summarized as follows.

When downshifting from 3rd gear to 2nd gear in the normal shift region PTH×A ₃ +F When upshifting from 2nd gear to 3rd gear in the normal shift region PTH×(A ₂ +A ₃ )+F 3rd gear → 2 in the kickdown region When downshifting to speed PTH×(A ₃ +A ₄ )+F When upshifting from 2nd gear to 3rd gear in the kickdown region PTH×(A ₂ +A ₃ +A ₅ )+F It is clear from the relational expressions shown in As in, for a shift in the normal shift region,
Hysteresis is provided depending on whether or not the pressure receiving area _A2 acts. In addition, in the shift in the kickdown region, in addition to the pressure receiving area A ₃ , A ₄
Hysteresis is provided depending on whether A ₂ +A ₅ acts or A ₂ +A ₅ >
_A4 ).

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

The invention is not limited to 2, 3 shift valves, but can be similarly applied to other shift valves such as 1, 2 shift valves.

Not limited to shift valves, for example, in automatic transmissions equipped with clutches that are automatically engaged and engaged by hydraulic actuators, axial pressure control is used to change the speed at which the automatic clutch is disengaged and when it is exclusively engaged. The present invention can be applied to any appropriate hydraulic control valve that requires hysteresis, such as when applied to a valve.

Not limited to those controlled by two control pressures such as governor pressure and throttle pressure, one control pressure is used to push the spool in the other direction for a balance spring that pushes the spool in one direction. It can be similarly applied to things that press against the surface.

In the embodiment, the hollow portion 18 is formed using the hole for mounting the balance spring 21, but it may be formed separately from the hole for mounting the balance spring 21. However, if the hollow part 18 is constructed using this mounting hole, the length of the spool 12 can be further shortened.

(Effects of the invention) As is clear from the above, the invention has the following effects:
The spool is formed with a hollow part that opens at its end face, and the inner end face of this hollow part is made to act as a pressure-receiving surface to bring about hysteresis, so the number of land parts to bring about this hysteresis is In addition, the outlet for controlling opening and closing can use the outlet that normally drains the end face of the spool, and the number of dedicated oil ports can be reduced, simplifying the structure. Furthermore, since the spool can be made smaller in length in the axial direction, the sliding resistance and inertia of the spool are reduced, resulting in a highly responsive spool.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment in which the present invention is applied to a shift valve. Figure 1 shows when the spool is in the first position, and Figure 2 shows when the spool is in the second position. is shown. FIG. 3 is an enlarged sectional view of the main part of FIG. 1. FIG. 4 is an enlarged sectional view of the main part of FIG. 2. FIG. 5 is a shift characteristic diagram obtained by the shift valve shown in FIGS. 1 and 2. 1: Main body, 2: Spool guide hole, 10: Throttle pressure introduction port (control pressure introduction port), 12: Spool,
18: Hollow part, 18a: Inner end surface, 19: Communication port.

Claims (1)

[Claims for Utility Model Registration] A main body in which a spool guide hole and a control pressure introduction port opening into the spool guide hole are formed; and a spool configured to be able to assume a second position and a second position, the spool having a hollow portion opening at an end face thereof and continuing to the hollow portion and opening at the outer circumferential surface of the spool. A communication port is formed, and the communication port communicates with the control pressure introduction port when the spool is in the first position, and is disconnected from the control pressure introduction port when the spool is in the second position. The end of the spool is configured to close the outlet when the spool is in the first position and open the outlet when the spool is in the second position, and the end of the spool is configured to close the outlet when the spool is in the first position and open the outlet when the spool is in the second position. The sliding displacement of the spool between the first position and the second position has hysteresis due to the action or non-action of a control pressure on the inner end surface of the hollow part through the spool. Hydraulic control valve for automatic transmission.